Penetrator projectile

ABSTRACT

A projectile in which a combination of interior elements, including a penetrator, a pyrotechnic delay column and an ignition charge are utilized to ignite a viscous uncured propellant after the projectile has been fired. The thus ignited propellant increases the velocity and effectiveness of the projectile.

mite States Patent [191 Dillinger et a1.

[ Aug. 28, 1973 PENETRATOR PROJECTILE [75] Inventors: Robert B. Dillinger; Howard H.

Payne, both of China Lake, Calif.

[73] Assignee: The United States of America as represented by the Secretary of the Navy, Washington, D'.C.

[22] Filed: May 30, 1972 [21] Appl. No.: 257,559

[52] US. Cl. 102/52, l02/DlG. 5 [51] Int. Cl. F421) 11/14, F421) 13/04 [58] Field of Search 102/49.3, 49.7, 52,

1 02/DIG. 5; 149/42 [5 6] References Cited UNlTED STATES PATENTS 3,277,825 10/1966 Maillard 102/52 3,097,602 7/1963 Turner l02/D1G. 5

3,399,088 8/1968 Christian et al. 149/42 3,302,570 2/1967 Marquardt 102/52 2,419,414 4/1947 Mohaupt 102/52 X 982,402 l/l9ll Wells 102/52 X 36,686 10/1862 Callender 102/52 X Primary ExaminerBenjamin A. Borchelt Assistant Examiner-J1. J. Tudor Attorney-R. S. Sciascia, Roy Miller and Lloyd E. K.

Pohl

[ ABSTRACT A projectile in which a combination of interior elements, including a penetrator, a pyrotechnic delay column and an ignition charge are utilized to ignite a viscous uncured propellant after the projectile has been fired. The thus ignited propellant increases the velocity and effectiveness of the projectile.

3 Claims, 1 Drawing Figure PENETRATOR PROJECTILE BACKGROUND OF THE INVENTION 1. Field of the Invention.

This invention relates to penetrator projectiles. More particularly, this invention relates to penetrator projectiles of the type in which propellant is utilized to increase the projectile velocity.

2. Description of the Prior Art.

Penetrator projectiles, i.e., projectiles which contain penetrators for armor piercing purposes and the like are known. It is also known that the velocity and thus the effectiveness of such projectiles can be increased by utilizing propellants within the projectiles. However, in the prior art solid propellants which ignite almost instantaneously upon firing of the projectiles in which they are contained have generally been used.

The use of solid propellants which are ignited instantaneously upon firing of the projectile has several drawbacks. Firstly, it is well known that solid propellants are susceptible to cracking upon being subjected to'high axial acceleration and the like and that cracks which develop in solid propellants often lead to explosions when the propellant is ignited. Secondly, enough solid propellant to be of great significance can not be incorporated into small projectiles. Thirdly, when the propellant is ignited almost unstantaneously as the projectile is fired, added thrust is obtained only during thefirst moments ofthe projectiles flight and not later when it could be better utilized. For these and other reasons, research leading to. the present invention was conducted. I

SUMMARY OF THE INVENTION The present invention provides a rocket assisted. penetrator projectile in which. uncured propellant is used in lieu of solid propellant and in which; the propellant I is ignited at a predetermined time well after the projectile has been fired. The propellantis-ignited by a combi-. nation. of events which include:

l. compression and heating of air inan adiabatic compression chamber by the penetrator when the projectile is fired;

2. actuation of a pyrotechnic delay column by the. heated air from theadiabatic compressionchamber;

3. actuation of an. ignition charge by, the pyrotechnic delay column; and

4. ignition. of the'propellant by the ignition charge.

The useof uncuredpropellant precludesthe possibility of propellant crackingtu nder thehigh axial accelerations encountered when the projectile isfired from a gun. Also, thepresent invention permits the use of a greater amount of propellant ina projectile ofagiven The single FlGUREisacross sectional view of a penetrator. projectile according to thisinvention,

DESCRIR IilON: OF THE PREFERRED EMBODIMENT;

Going first'to'the drawingin which like numerals are used to indicate likeparts, thesingle-FIGURE'isa cross sectional view .of a penetratorprojectile 1-1: according to this invention prior to firing. The projectile is made to fit into and be fired from a cartridge (not shown) which may be of any convenient size such that it will fit into an existing gun. For example, projectiles for guns having calibers in the range of from about 20 mm to about mm may be conveniently manufactured.

The projectile 11 comprises a hollow projectile housing 12 closed at its rear by nozzle 13 and nozzle closure 14. It is preferred that the nozzle throat be of ablative material of a type commonly used in rockets.

Loaded within the projectile housing is propellant 15. In practicing this invention, the propellant is an uncured propellant mix of the type ordinarily used to fabricate solid rocket propellant grains with the exception that no curing agent is added. That is, the propellant contains oxidizer particles such as NI-I.,Cl0 or the like, fuel particles such as Al or the like and binder material such as hydrozy or carboxy terminated polybutadiene or the like but no curing agentsuch as toluene diisocyanate which would form cross-links between polymeric chains of binder material and cause the binder to set. This the propellant may be described as a viscous suspension of oxidizer and fuel particles in a matrix of uncured binder material. A forward ullage void I6 is insured by means of a frangible or deformable diaphragm 17 which may be fabricated of plastic, rubber or the like and fastened in place by means of a suitable adhesive.

Rotating band support 18 provides support for a rotating band l9'which interacts with rifling in the barrel of a gun from which the projectile is fired to impart spin. The rotating band support may be either a washer like article located in the indicated position or a washer like article with a plurality of projections extending inwardly and resting on penetrator 20.

The penetrator 20 extends longitudinally from the forward end of the projectile towards the rear of the projectile and the aft end of the penetrator, along with tubular housing 21. and a partition 30 dividing the tubular' housing describes an adiabatic compression chamber 22'. The'penetrator is retained in fixed position with respect, to tubular housing 21 by means of a shear pin '28 or other form of retaining device.

containing uncured propellant of the type described" above is fired from a cartridge case contained in a rifled gun barrel, several related events occur.

Firstly, spin-is imparted to the projectile by interaction of the rotatingband 19 with the barrel rifling. This spincauses the viscous uncured propellant to be forced outwardly toward the projectile housing 12. The force is sufficientto cause the diaphragm 17 to rupture or deform which, in turn, permits the propellant tohave access to space provided byullage void. 16. The extra space plus continued'spin permits a'central core tobeformed in the propellant. The thus formed centralcore surrounds the penetrator 20 and tubular housing 21 and acts in a manner similar to a core in a solid propellant grain. That is, the propellant can be ignited in the core and will burn outwardly towards the projectile housing in a manner similar to that in which a cored solid propellant grain would burn.

As the projectile is fired, inertia causes the penetrator 20 to be forced toward the rear of the projectile severing shear pin 28 and compressing air in adiabatic compression chamber 22. The compressioncauses the air to heat and hot air passes through opening 26 actuating pyrotechnic delay column 24. The pyrotechnic delay column burns, from the front toward the rear, for a predetermined amount of time depending upon its length and upon the material from which it is fabricated until the flame actuates ignition charge 25. Flames jetting out of openings 27 from ignition charge 25, in turn, ignite the now cored propellant.

Once the propellant is ignited, pressure begins to build up within the projectile. When the pressure is sufficiently built up, nozzle closure 14 is blown out of nozzle l3 and the escaping gases propel the projectile in a manner similar to that in which a rocket is propelled.

In the practice of this invention, a wide variety of choices exist insofar as the length and material of the pyrotechnic delay column and material of the ignition charge are concerned. Also, a wide variety of choices exist insofar as the material of the propellant is concerned. The propellant should have the property wherein solid oxidizer and fuel particles remain suspended in the binder material and do not settle out upon storage of a propellant filled projectile.

This invention is advantageous in that ignition of the propellant does not occur instantaneously upon firing of the projectile but is delayed until late in the flight of the projectile when the maximum benefit can be derived from it. Also, the use of uncured propellant permits more propellant to be loaded into a given amount of space than is possible with solid propellant. Further, uncured propellant does not develop flaws when it is subjected to high stresses and the like and can thus be stored indefinitely without inspection.

it will be apparent to the reader that if desired the nose end of the projectile could contain a small warhead or the like to further increase effectiveness insofar as penetration of armor is concerned.

We claim:

1. A projectile comprising:

a. a hollow projectile housing closed at its aft end by a nozzle and nozzle closure, said projectile housing having at least one rotating band around its outer periphery;

b. a penetrator and a tubular housing centrally and longitudinally located within the projectile housing with the forward end of the penetrator at the foward end of the projectile housing and the aft end of the penetrator resting in the foward end of the tubular housing and describing an adiabatic compression chamber therewith, the aft end of said tubular housing being closed;

c. a pyrotechnic delay column located within the tubular housing in a position where heated air from the adiabatic compression chamber can contact it;

d. an ignition charge located within the tubular housing to the rear of and in contact with the pyrotechnic delay column;

e. a plurality of lateral openings in the tubular housing leading from the area in which the ignition charge is located to the exterior of the tubular housing; and

f. a'propellant mix comprising oxidizer particles and fuel particles suspended in uncured binder material surrounding said penetrator and tubular housing within the projectile housing.

2. A projectile according to claim 1 in which said propellant comprises NH particles and Al particles suspended in a binder material selected from uncured carboxy terminated polybutadiene and uncured hydroxy tenninated polybutadiene.

3. A projectile according to claim 1 in which said nozzle is ablative.

1 i It i 

2. A projectile according to claim 1 in which said propellant comprises NH4ClO4 particles and Al particles suspended in a binder material selected from uncured carboxy terminated polybutadiene and uncured hydroxy terminated polybutadiene.
 3. A projectile according to claim 1 in which said nozzle is ablative. 